Internal combustion engine



FIG. 1 is a perspective view of an internal combustion engine showing our present design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view.

The broken lines in FIG. 7 are included for the purpose of illustrating a portion of the internal combustion engine that forms no part of the claimed design. 

We claim, the ornamental design for an internal combustion engine, as shown and described. 